Removable Localizing Wire

ABSTRACT

A localizing wire comprising an anchor portion that can change shape from a collapsed shape to an expanded shape and thereby anchor within a tissue mass. A localizing wire having an exterior portion that can lie flat against the tissue mass. A localizing wire that can be repositioned or withdrawn without the need for the reinsertion of an introducer.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.10/904,666, filed Nov. 22, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to localizing wires and moreparticularly to a localizing wire which comprises an anchor portionhaving collapsible properties enabling the anchor portion to beretracted into a cannula lumen for repositioning or removal in a tissuemass. In another aspect, the invention relates to a localizing wireconfigured such that an externally extending portion of the wire can lieagainst the exterior of the tissue mass. In yet another aspect, theinvention relates to a method of using the localizing wire. In one otheraspect, the invention relates to a localizing wire that can be removedfrom a tissue mass without the re-introduction of a cannula.

2. Description of the Related Art

Localizing wires are well-known devices for marking areas, such aslesions, in a tissue mass, frequently breast tissue. When such a lesionis identified with a medical imaging technique, such as radiography orultrasonography, it is often desirable to position a localizing wire orother type of imaging marker near the lesion to facilitate locating thelesion during later procedures, such as biopsy or surgery.Alternatively, a localizing wire, tissue marker or staple can be placedin the tissue mass after a biopsy has been performed. In the lattercase, the localizing wire marks the location of the biopsy cavity forfuture procedures.

Localizing wires typically comprise an anchor portion implanted at thetissue site of interest, with a wire portion extending from the anchorportion to exit through the skin. A practitioner can then use the wireas a visual and tactile guide to the lesion rather than solely relyingon imaging techniques, which currently provide good 2-D images but not3-D images. During surgery, surgeons typically prefer a localizing wireto locate the lesion because it leads them straight to the biopsy site.

To implant a localizing wire, a needle, or cannula, is inserted into thetissue mass and, with guidance from an imaging system, is positionedwith its tip at a selected location at or near the lesion. Once theneedle is in place, the localizing wire is extended through the needleand out the tip into or adjacent the lesion where the hook on the end ofthe wire engages the tissue mass. Thereafter, the needle is removed fromthe tissue mass, and the localizing wire remains anchored in place bythe hook.

It is critical that the localizing wire be accurately placed at thedesired location within the tissue and remain in the desired location.Movement of the localizing wire after it is properly located andimplanted is very undesirable as it will not properly identify thelesion or the biopsy site if a follow-up surgery is required.

However, there is often a need to reposition the localizing wire afterthe initial implantation. For a variety of reasons, such as, forexample, the nature of the instrument used for implanting, the initialimplantation may not always be located at the desired site. Under suchcircumstances, the localizing wire will need to be repositioned. Thus, acontemporary localizing wire must perform the conflicting functions ofkeeping the localizing wire anchored at the desired implantation sitewhile permitting the repositioning of the localizing wire.

Prior localizing wires accomplished these conflicting functions by theanchor having a pointed, hook shape and being formed of a memory metal,such as Nitinol. When the localizing wire was stored in the cannula, theanchor was substantially straight and took on the hook shape only as itwas extended exteriorly of the cannula. As the anchor was extended fromthe cannula, it pierced the surrounding tissue and formed the hook shapeto anchor the localizing wire to the tissue. The localizing wire couldbe repositioned by withdrawing the anchor back into the cannula tostraighten out the hook. The cannula would then be repositioned and theanchor once again extended to anchor the wire. The curvature of the hookshape was great enough that the anchor would not defect in response toan external pulling on the wire.

While the prior localizing wire adequately accomplished the conflictingfunctions, it does have certain known disadvantages. One suchdisadvantage is that the tissue is pierced each time the localizing wireis repositioned, which causes additional trauma. It is better tominimize the trauma to the surrounding tissue for reduced recovery timeand the patient's comfort. Thus, there remains a need for a device thatcan reimplant or remove a localizing wire in a tissue mass after initialimplantation with minimal discomfort to a patient.

Another disadvantage of current localizing wires is that, afterimplantation, a portion of the localizing wire extends exteriorly of thetissue. This exteriorly extending portion of the localizing wireprojects away from the surface of the tissue mass. While the projectingof the exterior portion of the wire is useful for the surgeon inlocating the localizing wire during surgery, it creates the risk thatthe patient or someone else might accidentally catch the exteriorlyextending portion and pull or tug on the localizing wire, resulting inthe possible repositioning of the localizing wire inside the tissue.Such an accidental repositioning is very undesirable in that thelocalizing wire will no longer properly locate the lesion and it can bepainful for the patient. This is one of the reasons why localizing wiresare typically inserted just prior to the surgery and are not intended tobe left in the tissue mass for an extended period.

In practice, because of the several hour or several day delay betweenthe time that a biopsy is taken and the results of the tissue analysisis received, it is a common practice for an internal imaging marker,such as that disclosed in U.S. Pat. No. 6,575,991, to be placed at thebiopsy site. If the analysis of the tissue indicates that follow-upsurgery is required, then a localizing wire is placed within the tissueat the site of the internal imaging marker prior to surgery and thesurgeon uses the localizing wire to locate the biopsy site. It isdesirable to have a localizing wire that can be used instead of theinternal imaging marker to mark the biopsy site, left within the tissuefor an extended period of time, and used to guide the surgeon if surgeryis required or easily removed if surgery is not required.

SUMMARY OF THE INVENTION

The invention relates to a method of marking a lesion in a tissue masswith a localizing wire. The method comprises installing a localizingwire into a cannula having at least one lumen. The localizing wirecomprising a localizing thread and a localizing anchor having acollapsed shape delineating a first area in the at least one lumen andan expanded shape delineating a second area greater than the first areaoutside the at least one lumen. The cannula is inserted into the tissuemass. One of the localizing wire and the cannula is moved to place thelocalizing anchor outside the at least one lumen at a first selectedlocation relative to the lesion so that the localizing anchor expandsfrom the first to the second shape to exert an expansive force againstthe tissue mass.

The method can further comprise retracting the localizing anchor intothe at least one lumen to return the localizing anchor from the expandedshape to the collapsed shape. The cannula can then be repositioned torelocate the localizing member at a second selected location relative tothe lesion. The cannula can be withdrawn from the tissue mass with thelocalizing anchor remaining in the selected location and the localizingthread extending exterior of the tissue.

The method can further comprise reinserting the cannula into the tissuemass with the localizing thread extending through the at least one lumenfollowed by retracting the localizing anchor into the at least one lumento return the localizing anchor from the expanded shape to the collapsedshape, and then withdrawing the cannula with the localizing wire thereinto remove the localizing wire from the tissue mass.

The cannula can comprise multiple lumens, with an imaging markerinstalled into one of the lumens. The imaging marker or the cannula canthen be moved to place the imaging marker at a selected locationrelative to the lesion.

The invention also relates to a localizing wire for marking the locationof a lesion in a tissue mass. The localizing wire is adapted forplacement through at least one cannula lumen relative to the lesion. Thelocalizing wire comprises a localizing anchor for holding the localizingwire at a selected location within the tissue mass relative to thelesion. A localizing thread connects to the localizing anchor and issized to extend outside the tissue mass when the localizing anchor isheld at the selected location. The localizing anchor has a collapsedshape delineating a first area when the localizing anchor is in the atleast one lumen and an expanded shape delineating a second area largerthan the first area when the localizing anchor is outside the at leastone lumen.

The localizing thread can be made of wire. The anchor can have manydifferent shapes when expanded. Some of the expanded shapes include asquare, triangle, and circle. The anchor can also be disk shaped.

The localizing anchor and the localizing thread can be made of the samepiece or can be separate pieces connected together.

The localizing anchor can be withdrawn into the at least one lumen afterthe localizing anchor has been placed at the selected location relativeto the lesion by changing the anchor from the expanded shape to thecollapsed shape. The shape of the localizing anchor can be changed fromthe expanded shape to the collapsed shape by pulling on the localizingthread, whether the localizing wire is extending through the cannula ornot.

The at least one lumen comprises multiple lumens. An imaging marker canbe installed in one of the multiple lumens.

The localizing anchor is made from resilient material and inherentlyexpands from the collapsed shape to the expanded shape to exert a forceagainst the tissue mass, with the localizing anchor displacing but notpuncturing the tissue mass when the localizing anchor expands from thecollapsed to the expanded shape.

The invention relates to a method of marking a lesion in a tissue masswith a localizing wire. The method comprises installing a localizingwire into a cannula having at least one lumen. The localizing wirecomprising a localizing thread and a localizing anchor having acollapsed shape delineating a first area in the at least one lumen andan expanded shape delineating a second area greater than the first areaoutside the at least one lumen. The cannula is inserted into the tissuemass. One of the localizing wire and the cannula is moved to place thelocalizing anchor outside the at least one lumen at a first selectedlocation relative to the lesion so that the localizing anchor exerts anexpansive force against the tissue mass at the selected locationrelative to the lesion when the localizing anchor transitions from thecollapsed shape to the expanded shape.

The invention also relates to a localizing wire for insertion in atissue mass, comprising an anchor for at least temporarily fixing thelocalizing wire in the tissue mass, and a thread coupled to the anchorand being configured such that an exterior portion of the threadextending exteriorly of the tissue mass can lie substantially flatagainst the exterior of the tissue mass.

The thread can be configured to lie substantially flat against theexterior of the tissue mass by: the thread bending without plasticdeformation; the thread bending under its own weight; and/or selectingthe cross-sectional area and/or the Young's Modulus of the thread. Thethread can lie substantially flat against the tissue mass such thatthere is no gap between the tissue mass and the external portion of thethread near the insertion point into the tissue mass. While all of theexternal portion can lie flat against the tissue mass, at least aportion of the localizing wire near the insertion point is configured tolie substantially flat against the exterior of the tissue mass.

At least the portion of the thread near the insertion point can be madefrom annealed steel to provide the desired Young's Modulus.

The invention further relates to a method of positioning a localizingwire in a tissue mass, with the localizing wire comprising a thread andan anchor coupled to the thread. The method comprises inserting thelocalizing wire into the tissue mass such that the anchor is receivedwithin the tissue mass and a portion of the thread extends beyond theexterior of the tissue mass, and laying the external portion of thethread such that it is substantially flat against the exterior of thetissue mass.

The laying step can be accomplished by bending the external portion ofthe thread without any plastic deformation of the thread. The bending ofthe external portion can be effected by the weight of the externalportion. The laying can be such that there is substantially no gapbetween the exterior of the tissue mass and the portion of the externalportion near the insertion point of the localizing wire into the tissuemass. Also, the entire external portion can lie substantially flatagainst the exterior of the tissue mass.

The method can further comprise fixing the external portion to theexterior of the tissue mass. The fixing can be accomplished by tapingthe external portion to the exterior of the tissue mass.

In another aspect, the invention relates to a localizing wire forlocating a site within a tissue mass and implantable within the tissuemass using an introducer. The localizing wire comprising a thread towhich is mounted an anchor and an actuator. The anchor has an alterableconfiguration that is alterable between an anchor configuration and arelease configuration. The actuator is mounted to the localizing wirefor relative movement therewith between an anchor position, where theanchor assumes the anchor configuration, and a removal position, wherethe anchor assumes the release configuration. The actuator is accessibleexteriorly of the tissue mass after the localizing wire is implanted topermit the release of the anchor and the withdrawal of the localizingwire without a subsequent surgical procedure.

The actuator can comprise a shroud that is slidably mounted to thelocalizing wire, with the shroud at least partially covering the hookwhen the actuator is in the removal position. The shroud can be of alength such that a portion of the shroud extends beyond the exterior ofthe tissue mass after the localizing wire is implanted.

The shroud can further comprise an elongated sheath defining a hollowinterior in which the thread is slidably received. The sheath can beflexible. The sheath can have proximal and distal ends, wherein when thelocalizing wire is moved to the release position, the proximal end bearsagainst the anchor to move the anchor to the release configuration. Whenthe localizing wire is implanted the distal end extends beyond theexterior of the tissue mass.

The thread and sheath are configured such that the sheath can beslidably removed from the thread. The sheath can be of many forms and isespecially a tube or a coil spring. The tube can made of plastic, whichcan be transparent.

The combination of the sheath and the thread can be configured such thata portion of the combined thread and sheath extends exteriorly of thetissue mass and can lie substantially flat against the exterior of thetissue mass. The portion of the combined thread and sheath can have abending portion that bends without plastic deformation so that theportion of the combined thread and sheath can lie substantially flatagainst the exterior of the tissue mass. The bending portion can beconfigured to bend under its own weight. The portion of the combinedthread and sheath can be configured to lie substantially flat againstthe tissue mass by selecting at least one of the cross sectional areaand the Young's Modulus of the combined portion of the thread andsheath. The combined thread and sheath can be configured to liesubstantially flat against the tissue mass such that there is no gapbetween the tissue mass and the portion of the combined thread andsheath near the insertion point into the tissue mass.

The invention further relates to a method of implanting and removing,into a tissue mass, a localizing wire having a reconfigurable anchor.The method comprises: inserting the localizing wire into the tissuemass; configuring the anchor into an anchoring configuration where theanchor anchors the localizing wire in the tissue mass; reconfiguring theanchor from the anchoring configuration to a release configuration,where the anchor does not anchor the localizing wire in the tissue mass;and withdrawing the localizing wire with the anchor in the releaseconfiguration from the tissue mass.

The insertion of the localizing wire can comprise inserting anintroducer with a hollow interior into the tissue mass and inserting thelocalizing wire into the hollow interior of the introducer. Theintroducer can then be drawn away from the anchor after the inserting ofthe localizing wire in the tissue mass to expose the anchor. Thewithdrawing of the introducer comprises completely removing theintroducer from the tissue mass. The withdrawing of the introducereffects the reconfiguring of the anchor from the anchoring configurationto a release configuration.

The inserting of the localizing wire into the introducer can occur priorto or after the inserting of the introducer into the tissue mass. Theconfiguring of the anchor into the anchoring configuration can beeffected by relatively moving the introducer and the localizing wire.The relative movement of the introducer and the localizing wirecomprises moving the localizing wire relative to the introducer.

The configuring of the anchor into the anchor position need not occurafter the insertion of the localizing wire. The anchor can be in theanchoring configuration prior to the insertion of the localizing wire.

The method can further comprise sliding a sheath on the localizing wireto configure the anchor. The sheath can be slid toward the anchor toplace the anchor in the release configuration. Additionally, the sheathcan be slid away from the anchor to place the anchor in the anchoringconfiguration. The anchor can be at least partially received within thesheath when the anchor is in the release configuration.

The method can also comprise laying a portion of the localizing wireextending beyond the exterior of the tissue mass against the exterior ofthe tissue mass. The exterior portion of the localizing wire can besecured to the exterior of the tissue mass. The securing can be effectedby taping the exterior portion of the localizing wire to the exterior ofthe tissue mass.

The withdrawing of the introducer can comprise completely removing theintroducer from the tissue mass. The withdrawing of the introducer alsocan effect the reconfiguring the anchor from the anchoring configurationto a release configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a side view of a localizing wire introducer having a cannulacontaining a first embodiment of a localizing wire comprising a threadand an anchor, with the anchor extending from the cannula and in anexpanded condition.

FIG. 2 is a close-up perspective view of the end of the cannulaillustrated in FIG. 1.

FIG. 3 is a sectional view taken along view line 3-3 of FIG. 2illustrating the anchor received within the cannula and in a collapsedcondition.

FIG. 4 is an enlarged side view of the localizing thread and localizinganchor illustrated in FIG. 2 in the expanded condition.

FIG. 5 is an enlarged side view of a second embodiment of the localizingthread and localizing anchor illustrated in FIG. 4.

FIG. 6 is an enlarged side view of a third embodiment of the localizingthread and localizing anchor, with the anchor shown in the expandedcondition.

FIG. 6A is an enlarged view of the third embodiment shown in a collapsedcondition within the cannula.

FIG. 7 is an enlarged side view of a fourth embodiment of the localizingthread and localizing anchor.

FIG. 7A is an enlarged view of the fourth embodiment shown in acollapsed condition within the cannula.

FIG. 8 is an enlarged perspective view of a sixth embodiment of thelocalizing thread and localizing anchor.

FIG. 8A is an enlarged view of the sixth embodiment shown in a collapsedcondition within the cannula.

FIG. 9 is an enlarged perspective view of an alternate embodiment of acannula having a first lumen for receiving the localizing wire and asecond lumen.

FIGS. 10A-E are side elevation views illustrating a process of placingthe localizing wire at a selected location in a tissue of interest.

FIG. 11 is a drawing similar to FIG. 10E but using a second embodimentof the localizing wire that is configured to lay against the exterior ofthe tissue mass after insertion.

FIG. 12 is a side view of one embodiment of a localizing wire configuredto lie substantially flat against the exterior of the tissue mass.

FIG. 13 is a sectional view taken along line 13-13 of FIG. 12 andillustrating the cross-sectional area of the localizing wire.

FIG. 14 is a longitudinal sectional view of another embodiment of arepositionable and removable localizing wire comprising a localizingwire with a reconfigurable anchor and an actuator in the form of asheath for reconfiguring the anchor, with the anchor shown in ananchoring configuration and a release configuration (phantom lines).

FIG. 15 is a sectional view taken along line 15-15 of FIG. 14.

FIG. 16 is a longitudinal sectional view similar to FIG. 14, except thatthe sheath is moved relative to the localizing wire to effect thereconfiguring of the anchor from the anchoring configuration to therelease configuration, with the anchor being retracted within thesheath.

FIG. 17 is a longitudinal sectional view similar to FIG. 14 andillustrating an alternative sheath in the form of a coil spring.

DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

Referring now to the figures, and particularly to FIG. 1, an embodimentof the invention is illustrated comprising a localizing wire 10 operablycommunicating with a well-known introducer 12 having a cannula 14. Thecannula 14 comprises a distal end 30 having an insertion tip 34 and aproximal end 32. As best seen in FIG. 2, the cannula 14 defines a lumen16 through which the localizing wire 10 is placed.

Referring to FIGS. 1-4, the localizing wire 10 comprises a localizinganchor 40 and a localizing thread 42. When mounted in the introducer 12prior to implantation (FIG. 3), the anchor 40 is contained within thelumen 16 and a portion of the localizing thread extends exteriorly fromthe rear of the introducer (FIG. 1). However, it is not necessary forthe thread to extend exteriorly of the introducer. The thread can becontained within the interior of the introducer.

The localizing anchor 40 is fabricated of a resilient, physiologicallyinert material such as stainless steel or titanium wire, which canassume a first collapsed configuration in the lumen 16 as illustrated inFIG. 3, and a second expanded configuration outside the lumen 16 asillustrated in FIGS. 1, 2 and 4.

Referring to FIG. 4, the anchor 40 of the localizing wire 10 is shown ingreater detail. As illustrated, the anchor 40 is formed from the samewire as the thread 42. In other words, the anchor 40 is a continuationof the localizing thread 42, with an end 43 of the anchor 40 beingconnected to the thread 42 to complete the anchor 40. The end 43 can bebonded or welded to the thread 42 to form the connection.

The anchor 40 has a diamond or square shape when it is in the expandedcondition as illustrated in FIG. 4. The diamond shape is formed byproviding multiple bends 45 along the portion of the wire forming theanchor 40, which define therebetween corresponding segments 47. Thebends 45 function as hinges about which the segments can move to permitthe anchor to transition between the collapsed (FIG. 3) and expanded(FIG. 4) conditions.

While the anchor 40 is shown as a continuation of the thread 42 in FIG.4, FIG. 5 illustrates an alternative where the localizing anchor 40 andthe localizing thread 42 comprise separate elements, with the localizinganchor 40 attached to the localizing thread 42 through a suitableconnector 44, such as a crimped or interference-fit collar, a weld, orthe like. With a separate localizing anchor 40 and localizing thread 42,different materials can be used for each element. For example, thelocalizing anchor 40 could be formed of a material having a resiliencythat would be suitable for the shape-changing properties describedherein, but unsuitable for the localizing thread 42. Conversely, thelocalizing thread 42 could comprise a material having a stiffness thatwould be unsuitable for the localizing anchor 40.

The localizing anchor 40 can be formed with different shapes which canbe selected based upon, for example, the density of the tissue intowhich the localizing anchor 40 is to be placed, the size of the lesionof interest, the anchoring force required, and the like. In addition tothe diamond shape of FIG. 4, the localizing anchor 40 can have agenerally triangular shape in the expanded condition as shown in FIG. 6.The triangular shape is shown in the collapsed condition in FIG. 6A.FIGS. 7 and 7A illustrate another shape for the localizing anchor 40,which has the shape of a ring 48 in the expanded condition.

The anchor shapes illustrated in FIGS. 3-7A are similar in that they areof a thread type structure that encloses an area. When the anchor 40 isin the expanded condition, the enclosed area is much greater than whenin the collapsed condition. These shapes have no sharp edges that wouldpenetrate the surrounding tissue, yet they still anchor the localizingwire. The lack of penetrating edges reduces the trauma to the patientduring repositioning.

FIGS. 8 and 8A illustrate another localizing anchor 40 comprising a disc54, preferably formed with regularly-spaced fold lines 56 for collapsingthe disc 54, similar to an umbrella.

As illustrated in FIG. 9, a dual-lumen cannula 60 can be utilizedcomprising a primary lumen 62 and a secondary lumen 64. The primarylumen 62 carries the localizing wire 10, while the secondary lumen 64can carry a conventional imaging marker 66 such as that disclosed inU.S. Pat. No. 6,575,991, which is incorporated by reference, or can beused for the introduction of dye, irrigating fluid, pharmaceuticals, andthe like, such as that disclosed in co-pending U.S. patent applicationSer. No. 10/604,948, filed Aug. 28, 2003.

Referring now to FIGS. 10A-F, the localizing wire 10 is utilized asfollows. The localizing wire 10 is first loaded into the lumen 16 forintroduction of the cannula 14 into the tissue of interest 18. Asillustrated in FIG. 10A, the cannula 14 is introduced into the tissue 18so that the insertion tip 34 is at the location of interest, for exampleadjacent to or penetrating the lesion. As shown in FIG. 10B, thelocalizing wire 10 is then placed at the location of interest byrelatively moving the localizing wire 10 and the cannula 14 to exposethe anchor 40 beyond the cannula 14. The relative movement istraditionally accomplished by advancing the localizing wire 10 relativeto the cannula 14. However, the cannula can be retracted relative to thelocalizing wire 10 as disclosed in U.S. patent application Ser. No.10/707,043, filed Nov. 17, 2003, entitled Apparatus And Method ForImplanting A Preloaded Localization Wire, whose disclosure isincorporated by reference.

As the localizing anchor 40 exits the end of the cannula, it expandsfrom the collapsed to the expanded condition. As it expands into thesurrounding tissue, the anchor 40 compresses and/or displaces theadjacent tissue sufficiently to imbed the localizing anchor 40 in thetissue at the location of interest, but does not puncture the tissue aswith a hook-type anchor. If the localizing anchor 40 is notsatisfactorily placed at the selected location, the localizing wire 10can be retracted into the lumen 16 as shown in FIG. 10C by pulling onthe localizing thread 42 and drawing the anchor 40 back into thecannula. As the anchor 40 contacts the cannula 12, the interferencebetween the cannula 12 and the anchor collapses the anchor 40 from theexpanded to the collapsed condition.

As shown in FIGS. 10D-E, the cannula 14 can then be repositioned and thelocalizing wire 10 ejected from the lumen 16 into the new location. Thecannula 14 can then be removed from the tissue 18, leaving thelocalizing wire 10 in place with the localizing anchor 40 at thelocation of interest, and the localizing thread 42 extending outside thetissue 18 as with a conventional localizing wire.

Removal of the localizing wire 10 can be accomplished by passing thecannula 14 over the localizing thread 42 and inserting the cannula 14into the tissue 18 to the localizing anchor 40. The localizing anchor 40can then be retracted into the lumen 16, followed by removal of thecannula 14 from the tissue 18. Alternatively, the localizing anchor 40can be repositioned as discussed above. The localizing wire 10 can alsobe removed without the reintroduction of the cannula 14 by merelypulling the localizing thread 42 away from the tissue 18. The localizinganchor 40 will be urged into a collapsed configuration by the tissue 18to facilitate removal of the localizing anchor 40 from the tissue 18.

Prior localizing wires using a hook-shaped anchor that pierced thetissue could not be removed from the tissue without causing substantialtissue trauma unless a cannula was used. The localizing wire 12 can beremoved without a cannula with a sufficient force, but will not causethe same trauma to the surrounding tissue as the prior art devices sincethe anchor 40 does not rely on piercing the tissue for anchoring.

The localizing wire described herein has the advantage of being readilyrepositionable through retraction of the localizing wire into the lumenof a cannula after the localizing wire has been expelled from the lumen.Unlike prior art localizing wires having a hook-like configuration, thelocalizing wire does not puncture the tissue, whereas the prior artlocalizing wires puncture the tissue, complicating, if not precluding,removal of the localizing wire from the tissue. Furthermore, thelocalizing wire described herein can be removed from the tissue withoutthe necessity of reinserting a cannula into the tissue, therebyminimizing injury and discomfort to the patient.

It should be noted that while all of the embodiments disclose an anchorwith a completely bounded area that varies in size as the anchor isreconfigured from the release to the anchor configuration, it is withinthe scope of the invention for the anchors not to completely bound anarea. For example, the end 43 need not be attached to the thread 42.Instead, the end 43 could be unattached and be shaped to follow the leg47 or ring 48. The end 43 could even be excluded and the leg 47 or ring48 could just terminate prior to the thread 42. In either of theseconfigurations, the area would be effectively bounded, not actuallybounded and the bound area would be an effectively bound area. Thus, theterm area as used in this application includes both an actually boundarea and an effectively bound area.

FIG. 11 illustrates an alternative embodiment localizing wire 110comprising an anchor 140 and thread 142, with at least the thread 142being configured such that the exterior portion 143 of the thread 142will lie substantially flat against the exterior of the tissue 18. Theability of the thread 142 to lie against and not project substantiallyabove the tissue 18 significantly reduces the likelihood that the thread142 will be accidentally caught or hooked on a person, machine or otherobject. This significantly reduces the likelihood that the anchor 140will be dislodged from the position selected by the medicalprofessional. If the anchor 140 was moved from its initial position, itwould reduce the efficacy of the wire 110 in marking the biopsy site orlesion. The ability of the thread 142 to lie substantially flat againstthe tissue 18 also reduces the likelihood of trauma to the tissue 18caused by the jerking of the wire 110. Tape 146 or another similarmaterial can be used to hold the thread 142 in place against theexterior of the tissue 18.

Two factors are believed to be most relevant to configure the localizingwire 110 such that the thread 142 lies substantially flat against theexterior of the tissue 18: the second moment of area, I, and the Young'sModulus, E, of the material. The second moment of area, I, is a physicalproperty of the wire. It is representative of the distribution of themass of the object relative to the objects geometric axis. The greaterthe mass is distributed from the geometric axis, the greater the valueof I, and the more resistant the object is to bending about thegeometric axis.

The Young's Modulus essentially defines the stiffness of the material.All things being equal, the greater the Young's Modulus of a material,the greater the material will resist deflection.

In the context of a localizing wire, the Young's Modulus provides moreroom for adjustment to get the wire to lay flat against the tissue mass.This is because the cross-sectional area of the localizing wire hasbecome somewhat standardized along with the cannula. Thus, the Young'sModulus is the best candidate for ensuring that the external portion ofthe localizing wire will lie substantially flat against the tissue.

Regardless of which factor provides the most room for adjustment,ultimately what is required is that the second moment of area and theYoung's Modulus are selected such that the exterior portion of thelocalizing wire can be bent over and held against the tissue mass by asuitable fastener, such as tape. Preferably, the second moment of areaand the Young's Modulus are selected such that the bending does notresult in plastic deformation of the localizing wire as such deformationis more likely to cause the portion of the localizing wire within thetissue mass to move, which might negate the marking functionality of thelocalizing wire. It is more preferred that the second moment of area andthe Young's Modulus are selected such that the external portion of thelocalizing wire bends as needed under its own weight.

While it is preferred that the bending occur immediately at or aroundthe insertion point 145 of the localizing wire into the tissue mass, itis not necessary. If the localizing wire does not bend near theinsertion point 145 before the localizing wire lies flat against thetissue, a gap will form between the localizing wire and the tissuethereby effectively creating a small loop on which something couldcatch. The smaller this loop, the less likely an object will catch it.Thus, this loop should be minimized, but it should be done is such a waythat does not cause the shifting of the internal portion of thelocalizing wire, which would negate the marking functionality.

The “lying flat” functionality can be applied to any type of localizingwire and not just the localizing wires shown in FIGS. 1-10F. Forexample, FIGS. 12 and 13 illustrate a localizing wire 210 configured tolie flat against the exterior of the tissue mass and comprising astraight thread 242 and a hook-shaped anchor 240. The thread has agenerally circular cross section 244. Other cross sections can be used,such as oval, square, polygonal, and they can be either hollow or solid.

The circular cross section 244 as illustrated is typical of currentlocalizing wires that do not have the lie flat functionality. Thus, toachieve the lie flat functionality, the localizing wire is made from amaterial that provides a Young's Modulus that when combined with thecross section will permit the thread 242 to lie flat against the tissue18. For the described cross section, a suitable material is annealedsteel. The annealing of the steel reduces the stiffness of the material,which reduces the Young's Modulus, to permit the bending of the thread242 as needed to lie flat.

It is most preferred that localizing wire 242 bends as needed to lieflat under its own weight. Thus, the portion of the thread 242 extendingexteriorly of the tissue preferably has sufficient mass to effect thebending. For the example illustrated, the length of the threadpreferably takes into account a suitable safety margin to ensure thatthere is enough thread 242 exterior of the tissue mass to effect thebending.

It is worth noting that not the entire length of the thread need beconfigured to effect the lying flat of the thread on the exterior of thetissue mass. This portion of the thread can be referred to as thebending portion, which may extend along all or only a portion of thethread. It is anticipated that only that portion of the thread generallynear the insertion point 145 into the tissue mass need be so configuredif the bending is to minimize any gap between the exterior of the tissueand the thread. However, it is anticipated that for manufacturingsimplicity, the entire thread will be so configured, especially if thematerial is treated to select the desired Young's Modulus.

FIGS. 14-16 illustrate another embodiment of a localizing wire 310 thatcan be repositioned like the localizing wire 10. Additionally, thelocalizing wire 310 can be withdrawn from the tissue mass 18 after thelocalizing wire 310 is implanted and after the removal of the cannula14, without the reintroduction of the cannula 14.

The localizing wire 310 comprises a configurable anchor 340 and a thread342. An actuator for reconfiguring the configurable anchor in the formof a sheath 350 is slidably mounted on the thread 342. As illustrated,the anchor 340 is made of a resilient material, such as Nitenol, thatpermits the anchor 340 to be configured between an anchoringconfiguration (FIG. 13), where it has a hook-like shape for anchoring inthe tissue mass, and a release configuration (shown in phantom in FIG.14), where the anchor is generally straight relative to the thread 342to release the anchor 340 from the tissue mass 18.

It should be noted that while the anchor 340 illustrated in FIGS. 14-16is known in the art, other configurable anchors, such as those shown inFIGS. 1-9, can also be used.

The sheath 350 has a proximal end 352 near the anchor 340 and anopposing distal end 354. The sheath 350 defines a hollow interior 356 inwhich the thread 342 is received to slidably couple the sheath 350 andthread 342 for relative slidable movement. The sheath 350 functions asan actuator for moving the anchor between the anchoring and releaseconfigurations. When the sheath 350 is withdrawn from the anchor 340(FIG. 14), the anchor 340 because of its resiliency will inherentlyassume the anchoring configuration. To effect a change in theconfiguration of the anchor 340, the sheath 350 is advanced toward theanchor 340 by the relative movement of the thread 342 and sheath 350. Asthe proximal end 352 of the sheath 350 is advanced toward the anchor340, the proximal end 352 comes into contact with the anchor 340. Thecontinued advancement of the sheath 350 causes the anchor 340 tostraighten as it is received within the interior 356 of the sheath 350and thereby effect the reconfiguring of the anchor 340 into the releaseconfiguration.

It should be noted that the anchor 340 need not be completely receivedwithin the interior 356 of the sheath 350 for the anchor 340 to be inthe release configuration. The anchor 340 need only be straightenedenough that the anchor will release from the tissue. The completereceipt of the anchor 340 in the interior 356 of the sheath 350 ispreferred as that ensures that the anchor 340 is straight enough and itwill cause the least amount of tissue damage when the localizing wire ismoved or withdrawn.

The sheath 340 is illustrated as being transparent, but it can have anydesired degree of opacity. The sheath 340 is preferably made from asuitable plastic. The sheath 340 can also have any suitable type ofimageable markings that permit the location of the sheath 340,especially the proximal end 352, which would permit the user to view therelative location of the proximal end 352 and the anchor 340, which canalso have such imageable markings. Such imageable markings are wellknown in the art and vary on the type of imaging technique being used.

The implanting of the localizing wire 310 is essentially identical tothat described for the localizing wire 10. In short, an introducer,typically a cannula 14, is inserted into the tissue mass 18. Thelocalizing wire is inserted through the lumen of the cannula and out theopen end of the cannula, where the anchor 340 can anchor in the tissuemass 18. Once the localizing wire is properly positioned, the cannula 14is withdrawn.

The localizing wire 310 can be inserted along with the cannula 14 orafter the cannula 14 is inserted. The localizing wire 310 can beinserted with the anchor 340 either in the anchoring configuration orthe release configuration. If it is inserted in the releaseconfiguration, it will, of course, need to be put in the anchoringconfiguration to anchor.

After the withdrawal of the cannula 14, the localizing wire 310 can berepositioned or withdrawn without the need for reinserting the cannula14, as is now required. The localizing wire 310 can be repositioned orwithdrawn by relatively moving the thread 342 and sheath 350 such thatthe anchor is reconfigured from the anchoring configuration to therelease configuration. In the release configuration, the localizing wirecan be repositioned or withdrawn. If repositioned, the sheath 350 andthread 342 are relatively moved to configure the anchor in the anchoringconfiguration and re-anchor the localizing wire. If withdrawn, the usermerely pulls on the exterior portion of the localizing wire 310.

The reconfiguring of the anchor 340 after the implanting of thelocalizing wire 310, can be done by manipulating the portions of thesheath 350 and thread 342 (sliding them relative to each other) thatextend exteriorly of the tissue mass. This prevents the need forreinserting the cannula 14 as is currently done.

The ability to remove the localizing wire 310 without the reintroductionof the cannula 14 is very beneficial. Often the localizing wire 310 willbe inserted in a tissue mass at the location of a biopsy site. Thelocalizing wire 310 is left in while analysis is run on the biopsyspecimen. It can take from a few hours to a few days to complete theanalysis. This is too long of a time to leave the cannula 14 inserted inthe patient as the rigid cannula 14 is uncomfortable, if not painful,when left in. It can also increase the risk of infection since the lumenof the cannula 14 creates an open air pathway into the tissue mass 18.In cases where the analysis confirms that no follow-up surgicalprocedure need be done, such as a tissue removal, the localizing wirecan easily be removed without reintroducing the cannula 14, eliminatingadditional tissue damage and discomfort for the patient, not to mentionthe cost of the cannula insertion procedure.

It should be noted that the cannula 14 need not be completely withdrawnfrom the tissue mass for the sheath 340 to be used to effect thereconfiguring of the anchor. The cannula 14 need only be withdrawn awayfrom the anchor a sufficient amount such that the cannula 14 does notinterfere with the reconfiguring of the anchor. It is expected that inmost cases the cannula will be complete removed because of the increasedrisk of infection and accidental tissue damage if it is left in placed,especially since the cannula will no longer be needed for the removal ofthe localizing wire because of the sheath.

It should also be noted that during insertion the anchor could extendbeyond the end of the sheath but would still be constrained in therelease configuration by the cannula, and the withdrawal of the cannulaaway from the anchor would effect the reconfiguration of the anchor tothe anchor configuration. The sheath could then be used to reconfigurethe anchor from the anchor configuration to the release configurationwhen it is desired to remove the localizing wire.

FIG. 17 illustrates an alternative localizing wire 410 having analternative design for the sheath in the form of a coil spring 450. Thecoil spring 450 is wound such that it defines a hollow interior 456 forreceiving the thread 342. The coil spring 450 has a proximal end 452 anda distal end 454. The operation of the localizing wire 410 with the coilspring 450 is identical to that previously described.

The localizing wires 310 and 410 can be configured to lay flat againstthe exterior of the tissue mass 18 as previously described. With thelocalizing wires 310, 410, the characteristics of both the thread 342,442 and the sheath 350, 450 must be taken into account to achieve thelaying flat functionality.

While the invention has been specifically described in connection withcertain specific embodiments thereof, it is to be understood that thisis by way of illustration and not of limitation. Reasonable variationand modification are possible within the scope of the forgoingdisclosure and drawings without departing from the spirit of theinvention which is defined in the appended claims.

1. A localizing wire for locating a site within a tissue mass andimplantable within the tissue mass using an introducer, comprising: ananchor having an alterable configuration that is alterable between ananchor configuration and a release configuration; a thread coupled tothe anchor; and an actuator mounted to the localizing wire for relativemovement therewith between an anchor position, where the anchor assumesthe anchor configuration, and a removal position, where the anchorassumes the release configuration; wherein the actuator is accessibleexteriorly of the tissue mass after the localizing wire is implanted topermit the release of the anchor and the withdrawal of the localizingwire without a subsequent surgical procedure.
 2. The localizing wireaccording to claim 1, wherein the actuator comprises a shroud slidablymounted to the localizing wire, with the shroud at least partiallycovering the hook when the actuator is in the removal position.
 3. Thelocalizing wire according to claim 2, wherein the shroud is of a lengthsuch that a portion of the shroud extends beyond the exterior of thetissue mass after the localizing wire is implanted.
 4. The localizingwire according to claim 3, wherein the shroud comprises an elongatedsheath defining a hollow interior in which the thread is slidablyreceived.
 5. The localizing wire according to claim 4, wherein thesheath comprises proximal and distal ends, wherein when the localizingwire is moved to the release position, the proximal end bears againstthe anchor to move the anchor to the release configuration.
 6. Thelocalizing wire according to claim 5, wherein the distal end extendsbeyond the exterior of the tissue mass when the localizing wire isimplanted.
 7. The localizing wire according to claim 4, wherein thethread and sheath are configured such that the sheath can be slidablyremoved from the thread.
 8. The localizing wire according to claim 4,wherein the sheath is a tube.
 9. The localizing wire according to claim8, wherein the tube is made of plastic.
 10. The localizing wireaccording to claim 9, wherein the plastic is transparent.
 11. Thelocalizing wire according to claim 4, wherein the sheath is a coilspring.
 12. The localizing wire according to claim 4, wherein thecombination of the sheath and the thread are configured such that aportion of the combined thread and sheath extends exteriorly of thetissue mass and can lie substantially flat against the exterior of thetissue mass.
 13. The localizing wire according to claim 12, wherein theportion of the combined thread and sheath has a bending portion thatbends without plastic deformation so that the portion of the combinedthread and sheath can lie substantially flat against the exterior of thetissue mass.
 14. The localizing wire according to claim 13, wherein thebending portion is configured to bend under its own weight such that theportion of the combined thread and sheath can lie substantially flatagainst the exterior of the tissue mass.
 15. The localizing wireaccording to claim 12, wherein the portion of the combined thread andsheath is configured to lie substantially flat against the tissue massby selecting at least one of the cross sectional area and the Young'sModulus of the combined portion of the thread and sheath.
 16. Thelocalizing wire according to claim 12, wherein the combined thread andsheath are configured to lie substantially flat against the tissue masssuch that there is no gap between the tissue mass and the portion of thecombined thread and sheath near the insertion point into the tissuemass.
 17. The localizing wire according to claim 4, wherein the sheathis removably mounted to the localizing wire.
 18. The localizing wireaccording to claim 4, wherein the sheath is flexible.